Influence of stress on reproduction: Involvement of the Melanocortin receptor type 2 in ovarian response to adrenocorticotropic hormone.

EMILIA HUBER; HUGO H. ORTEGA; FLORENCIA REY; AYELEN N. AMWEG; LUCAS ETCHEVERS; NATALIA R. SALVETTI

Congreso; LXIII Reunión anual de la Sociedad Argentina de Investigación Clínica.; 2018

Cattle undergo numerous environmental, management and nutritional stressors throughout the reproductive cycle. In response to stress, adrenocorticotropic hormone (ACTH) acts on adrenal gland promoting glucocorticoids synthesis and secretion, which are implied in metabolism, inflammatory response and reproduction. The aim of the present study was to evaluate the protein expression of Melanocortin Receptor 2 (ACTH receptor, MC2R) and its accessory protein (MRAP2) in the preovulatory follicles in the ovary of cows treated with ACTH. Holstein cows (n=16) were divided into two groups: Control group (administrated with saline solution) and ACTH group (administrated with 100 UI of ACTH) every 12 hours during 4 days before expected time of ovulation until ovariectomy. MC2R expression was higher in theca interna cells from preovulatory follicles of ACTH group relative to Control group (p< 0.05), whereas in granulosa cells it was similar in both groups (p> 0.05). MRAP2 expression was similar in both cell types from both groups analysed (p> 0.05). In addition, higher concentration of cortisol was detected in follicular fluid and serum of ACTH group relative to Control group (p< 0.05). Also, higher concentration of progesterone was detected in serum of ACTH group (p< 0.05). These results show that the bovine ovary is able to respond locally to the ACTH released as a consequence of stress. Moreover, these results indicate that ACTH, through its specific receptor, may be involved in regulatory mechanisms related to ovarian functions such as ovulation, steroidogenesis and in the pathophysiology of various reproductive diseases in cattle.